Microchannel plates (MCPs) are used to detect very weak signals generated by ions and electrons. For example, microchannel plates are commonly used as electron multipliers in image intensifying devices. A microchannel plate is a slab of high resistance material having a plurality of tiny tubes or slots, which are known as microchannels, extending through the slab. The microchannels are parallel to each other and may be positioned at a small angle to the surface. The microchannels are usually densely distributed. A high resistance layer having high secondary electron emission efficiency is formed on the inner surface of each of the plurality of channels so that it functions as a dynode. A conductive coating is formed on the top and bottom surfaces of the slab comprising the microchannel plate.
In operation, an accelerating voltage is applied across the conductive coatings on the top and bottom surfaces of the microchannel plate. The accelerating voltage establishes a potential gradient between the opposite ends of each of the plurality of channels. Ions and electrons traveling in the plurality of channels are accelerated. These ions and electrons collide against the high resistance layer having high secondary electron emission efficiency, thereby producing secondary electrons. The secondary electrons are accelerated and undergo multiple collisions with the resistance layer. Consequently, electrons are multiplied inside each of the plurality of channels. The electrons eventually pass through the anode end of each of the plurality of channels. The electrons can be detected or can be used to form images on an electron sensitive screen, such as a phosphor screen.